KR20180026606A - Flexible porous nanofiber composite having high specific surfcae area and method of manufacturing the same - Google Patents

Abstract

A porous nanofiber composite which is flexible and can have a high specific surface area by using a thermal etching process and a manufacturing method thereof are disclosed. The method for manufacturing flexible porous nanofibers having high specific surface area according to the present invention comprises the following steps: (a) adding a porous material to a solvent, stirring the mixture, and adding a polymer resin to form a composite solution; (b) electrospinning the composite solution on a substrate, followed by drying to form the porous nanofiber composite; and (c) etching the surface of the porous nanofiber composite by subjecting the porous nanofiber composite to thermal etching treatment.

Description

TECHNICAL FIELD [0001] The present invention relates to a flexible porous nano fiber composite having a high specific surface area and a method of manufacturing the same. [0002] The present invention relates to a flexible porous nano-

The present invention relates to a porous nanofiber composite material and a method of manufacturing the same, and more particularly, to a porous nanofiber composite material which is flexible and can secure a high specific surface area by using a thermal corrosion process, and a method of manufacturing the same.

Nanofibers are materials that have a nanoscale diameter and a micro-scale in the fiber length direction. Thus, nanofibers have both functional advantages coming from the nanoscale structure and ease of handling from the microscale. As described above, the nanofibers have a three-dimensional network structure and thus have excellent mechanical properties and ease of handling.

Such nanofibers can be prepared by solution spinning, melt spinning, drawing, self-assembly, chemical vapor deposition (CVD), electrospinning, etc. Among them, the electrospinning method is known as the most effective method for fiber formation, mass production, and application.

A related prior art is Korean Patent Laid-Open Publication No. 10-2012-0063167 (published on June 15, 2012), which discloses porous metal oxide nanofibers and a method for producing the same.

An object of the present invention is to provide a porous nanofiber composite which is flexible and can secure a high specific surface area by using a thermal corrosion process, and a method of manufacturing the same.

In order to accomplish the above object, the present invention provides a process for producing a flexible porous nanofiber composite having a high specific surface area, comprising the steps of: (a) adding a porous material to a solvent and stirring the mixture, ; (b) electrospinning the composite solution on a substrate, followed by drying to form a porous nanofiber composite; And (c) etching the surface of the porous nanofiber composite by subjecting the porous nanofiber composite to thermal erosion treatment.

According to an aspect of the present invention, there is provided a flexible porous nanofiber composite material having a high specific surface area, the porous porous nanofiber composite material including a porous material and a polymer resin layer surrounding the surface of the porous material, And a part of the porous material is exposed to the outside.

The flexible porous nano fiber composite having a high specific surface area according to the present invention and the method for manufacturing the same can be produced by electrospinning and drying a composite solution containing a polymer resin, a solvent and a porous material, and then, through a thermal etching process, A part of the porous material is exposed to the outside of the polymer resin layer and the adsorption performance can be improved by exposing a part of the porous material.

Accordingly, the flexible porous nano fiber composite material having a high specific surface area according to the present invention and its manufacturing method can ensure excellent flexibility and handleability, which are merits of nanofibers, and have advantages of wide specific surface area The adsorption performance can be secured at the same time.

As a result, the flexible porous nano fiber composite having a high specific surface area according to the present invention and a method for producing the same have a porous material and a polymer resin layer surrounding the porous material, wherein a part of the polymer resin layer is etched A part of the porous material is exposed to the outside, and has a high specific surface area of 500 to 850 m 2 / g.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a process flow diagram illustrating a method of making a flexible porous nanofiber composite having a high specific surface area according to an embodiment of the present invention.
2 is a diagram showing the results of TGA and DTG experiments.
3 is a photograph showing SEM and AFM photographs of a sample according to Comparative Example 1. Fig.
4 is a photograph showing SEM and AFM photographs of a sample according to Example 1. Fig.
5 is a photograph showing SEM and AFM photographs of a sample according to Example 2. Fig.
6 is a photograph showing SEM and AFM photographs of a sample according to Example 3. Fig.
7 is a graph showing the results of measurement of C and Si component ratios for the samples according to Examples 1 to 3 and Comparative Example 1. Fig.
8 is a graph showing the XRD measurement results of the samples according to Examples 1 to 3 and Comparative Examples 1 and 2;
9 is a graph showing the results of specific surface area measurement for the samples according to Examples 1 to 3 and Comparative Examples 1 and 2.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a flexible porous nano fiber composite having a high specific surface area according to a preferred embodiment of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

1 is a process flow diagram illustrating a method for producing a flexible porous nanofiber composite having a high specific surface area according to an embodiment of the present invention.

Referring to FIG. 1, a method for fabricating a flexible porous nanofiber composite having a high specific surface area according to an embodiment of the present invention includes a complex solution forming step (S110), an electrospinning step (S120), and a thermal corrosion step (S130).

Complex solution formation

In the complex solution forming step (S110), the porous material is added to a solvent and stirred, and then a polymer solution is added to form a complex solution.

At this time, any one selected from polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PDVF), and epoxy resin may be used as the polymer resin, and polyvinylpyrrolidone (PVP) is more preferable.

Examples of the solvent include ethanol, acetylacetone, dimethylformamide (DMF), octanol, tetradecane, pentanol, dipropylene glycol monomethyl ether, Ethylene glycol and the like may be used.

Particularly, in the present invention, it is preferable that the composite solution is composed of 15 to 35% by weight of a polymer resin, 5 to 35% by weight of a porous substance, and the remaining solvent.

When the addition amount of the polymer resin is less than 15% by weight of the total weight of the composite solution, the concentration of the solution is low, and it is likely to accumulate in the form of droplets to form a bead-shaped fibrous phase. On the contrary, when the addition amount of the polymer resin exceeds 35% by weight of the total weight of the composite solution, there is a problem that the stability upon formation of the nanofiber composite is deteriorated due to excessive shrinkage.

The porous material has a large specific surface area, thereby improving the adsorption performance and enhancing the strength. For this purpose, it is preferable to use at least one of zeolite and activated carbon as the porous material.

When the amount of the porous material to be added is less than 5% by weight of the total weight of the composite solution, the amount of the porous material to be added is insufficient and it may be difficult to secure the elongation and strength. On the other hand, when the amount of the porous material added exceeds 35 wt% of the total weight of the composite solution, the brittleness increases depending on the nature of the fiber shape, and the tensile strength is rather reduced.

It is more preferable that the above-described complex solution forming step (S110) is subdivided into a first mixing step, a second mixing step and a third mixing step.

In the primary mixing process, the porous material is added to the solvent and subjected to ultrasonic treatment for 7 to 8 hours for primary mixing.

In the secondary mixing process, the primary mixed products are mixed at a speed of 200 to 400 rpm using a stirrer and then mixed in a secondary mixer.

When the stirring speed is less than 200 rpm in the secondary mixing process, there is a fear that the porous material and the solvent are not uniformly mixed. On the other hand, if the stirring speed exceeds 400 rpm, it may be a factor that raises the manufacturing cost without any further effect, which is not economical.

In the tertiary mixing process, the polymer resin is added to the secondary mixed resultant, and the resulting mixture is stirred at a speed of 1000 to 2000 rpm through a stirrer to perform tertiary mixing.

If the stirring speed is less than 1000 rpm during the third mixing process, there is a possibility that the porous material and the polymer resin are not uniformly mixed. On the contrary, when the stirring speed exceeds 2000 rpm, it may be a factor that raises the manufacturing cost without any further effect, which is not economical.

Electric radiation

In the electrospinning step (S120), the composite solution is electrospun on a substrate and then dried to form a porous nanofiber composite.

Such electrospinning is preferably carried out by injecting the complex solution into a syringe and then discharging the solution onto the substrate at a rate of 0.1 to 3.0 ml / hr using a syringe pump.

Particularly, it is preferable that the electrospinning is carried out under the conditions of a radiation voltage of 15 to 18 kV and a radiation distance of 5 to 15 cm, and a syringe having a nozzle diameter of 20 to 30 G is preferably used. Here, the spinning distance means a distance between the substrate of the object to be spinned and the nozzle of the syringe.

When the radiation voltage is less than 15 kV, the manufacturing time is excessively increased, which may increase the manufacturing cost, and it may be difficult to form a uniform film quality. Conversely, when the radiation voltage exceeds 18 kV, it can not be economical because it can only cause a rise in the cost of effect increase. When the spinning distance is less than 5 cm, there is a possibility that the film quality characteristic is deteriorated due to interference by the nozzles. Conversely, if the spinning distance exceeds 15 cm, it may be difficult to obtain a uniform film.

The porous nanofiber composite is preferably formed to a thickness of 100 to 5000 탆. When the thickness of the porous nanofiber composite is less than 100 탆, the thickness of the porous nanofiber composite is too thin, so that it is difficult to exhibit the adsorption performance properly. On the contrary, when the thickness of the porous nanofiber composite is more than 5000 탆, the thickness of the product when applied to the nanofiber filter for removing VOC (volatile organic compounds) adsorption may decrease the practicality.

At this time, drying is preferably carried out at 70 to 90 ° C for 5 to 20 hours. If the drying temperature is less than 70 ° C or less than 5 hours, there is a possibility that sufficient drying is not achieved. On the contrary, when the drying temperature exceeds 90 ° C or the drying time exceeds 20 hours, it can not be economically feasible because it can only increase the manufacturing cost without increasing the effect.

After this drying, all of the solvent is volatilized and removed. As a result, the porous nanofiber composite material can be composed of a porous material and a polymer resin layer surrounding the surface of the porous material. At this time, the porous material may have a structure in which the entire surface is sealed by the polymer resin layer.

Thermal corrosion

In the thermal erosion step (S130), the porous nanofiber composite is thermally etched to etch a part of the surface.

As described above, part of the polymer resin layer is removed by etching a part of the surface of the porous nanofiber composite by thermal erosion treatment, and a part of the porous material is exposed to the outside. Accordingly, a part of the surface of the porous nanofiber composite is removed by etching, so that it has an irregular surface structure.

If the thermal corrosion step (S130) is not performed, the porous material is completely covered with the polymer resin layer, so that the porous material having excellent adsorbability is sealed by the polymer resin layer, so that the adsorption function is not exhibited properly .

Accordingly, in this step, only the surface of the porous nanofiber composite material, particularly a part of the polymer resin layer of the porous nanofiber composite material, is selectively removed to have an irregular surface to expand the surface area of the polymer resin layer, The adsorption performance can be further improved by exposing a part of the porous material to be sealed to the outside.

Particularly, in the thermal erosion step (S130), when the temperature of the erosion treatment is increased, the surface of the polymer resin layer is etched in the early stage to expose a part of the porous material to the surface to increase the surface area. However, In this case, it was confirmed that the polymer had a high specific surface area but had a loss of flexible characteristics due to the etching to the polymer resin layer constituting the skeleton. At this time, the thermal erosion treatment time can be performed for 20 minutes to 3 hours, but this is merely an example and need not be limited thereto.

Therefore, although the temperature range suitable for the thermal erosion step (S130) may vary depending on the kind of the polymer and the added amount of the porous material, the polymer surface etching zone having a high surface area while maintaining the flexibility through the TGA experiment ) Was found to be 250 to 450 ° C.

At this time, if the thermal corrosion treatment temperature is less than 250 ° C, heat corrosion may not be smoothly performed, and thus it may be difficult to increase the specific surface area. On the contrary, when the thermal corrosion treatment temperature exceeds 450 ° C, the polymer resin layer constituting the skeleton of the porous nanofiber composite is excessively etched so that the specific surface area is expanded but the flexibility is lost.

The flexible porous nanofiber composite having a high specific surface area prepared by the above-described processes (S110 to S130) is prepared by electrospinning and drying a composite solution containing a polymer resin, a solvent and a porous material, and then performing a thermal etching process A part of the porous resin material is exposed by exposing a part of the porous resin material to thereby provide a flexible and high specific surface area. In addition, since a part of the porous material is exposed to the outside of the polymer resin layer, do.

Therefore, the flexible porous nanofiber composite having a high specific surface area prepared by the method according to the embodiment of the present invention can ensure an excellent flexibility and handling property, which is an advantage of the nanofiber, It is possible to secure an excellent adsorption performance at the same time.

As a result, the flexible porous nanofiber composite having a high specific surface area prepared by the method according to an embodiment of the present invention comprises a porous material and a polymer resin layer surrounding the surface of the porous material, wherein a part of the polymer resin layer is subjected to a heat- So that a part of the porous material is exposed to the outside and has a high specific surface area of 500 to 850 m 2 / g.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Sample preparation

Example 1

45 g of Y-zeolite powder sintered for 1 hour in a state of being heated to 500 ° C at a heating rate of 5 ° C / min was added to 100 ml of ethanol and subjected to ultrasonic treatment for 7 hours, followed by primary mixing, Followed by secondary mixing at a speed of 300 rpm, followed by tertiary mixing at a speed of 1,500 rpm using a stirrer while adding 50 g of PVP to prepare a composite solution.

Next, the composite solution was injected into a syringe at a rate of 0.5 ml / hour using a syringe pump, and then electrospun on a glass substrate, followed by drying at 80 ° C. for 6 hours to obtain a nanofiber Complex. At this time, the diameter of the tip was 20 G, the radial voltage applied to the nozzle was 10 kV, and the distance from the glass substrate was 10 cm.

Next, a part of the surface of the nanofiber composite was etched by thermal erosion treatment at 300 DEG C for 1 hour to prepare a porous nanofiber composite sample.

Example 2

A porous nanofiber composite sample was prepared in the same manner as in Example 1, except that the thermal corrosion treatment was carried out at 350 占 폚 for 1 hour.

Example 3

A porous nanofiber composite sample was prepared in the same manner as in Example 1, except that thermal etching treatment was performed at 400 占 폚 for 1 hour.

Comparative Example 1

A nanofiber composite sample was prepared in the same manner as in Example 1 except that no thermal erosion treatment was performed.

Comparative Example 2

A Y-zeolite powder sample sintered for 1 hour in a state heated to 500 ° C at a heating rate of 5 ° C / min was prepared.

2. Property evaluation

2 is a diagram showing the results of TGA and DTG experiments.

As can be seen through the TGA and DTG curves, as shown in FIG. 2, the zeolite-PVP nanofiber composite has a <a> solvent removal zone, <b> defects It has been confirmed that the microparticles are subdivided into a no defect zone, a polymer surface etching zone and a pure zeolite fiber zone.

At this time, it was confirmed that the surface area of the polymer having a high specific surface area while maintaining flexibility was in the range of 250 to 450 ° C. as shown in TGA analysis results, which is consistent with the samples of Examples 1 to 3.

FIG. 3 is a photograph showing SEM and AFM photographs of a sample according to Comparative Example 1, FIG. 4 is a photograph showing SEM and AFM photographs of a sample according to Example 1, FIG. 6 is a photograph showing SEM and AFM photographs of the sample according to Example 3. FIG.

Referring to FIG. 3, as can be seen from the SEM and AFM images, it can be seen that Comparative Example 1 in which no thermal etching treatment was performed has a smooth surface.

4 to 6, as can be seen from the SEM and AFM images, as the temperature of the thermal etching process is increased, the polymer on the surface is gradually etched and the zeolite particles are exposed to the surface of the nanofiber composite .

7 is a graph showing the results of EDS analysis on the samples according to Examples 1 to 3 and Comparative Example 1. Fig.

Referring to FIG. 7, according to the result of EDS (Energy Dispersive X-ray Spectroscopy) analysis, it is confirmed that the content of Si linearly increases as the temperature of thermal corrosion treatment increases, while the content of C linearly decreases .

8 is a graph showing the XRD measurement results of the samples according to Examples 1 to 3 and Comparative Examples 1 and 2.

As shown in FIG. 8, the Y-zeolite peaks were observed in the samples according to Examples 1 to 3 and Comparative Examples 1 and 2, as can be seen from the XRD measurement results. As a result, the effect of the electrospinning process and the thermal erosion treatment process on the structure of the zeolite is weak.

Table 1 shows the results of evaluating physical properties of the samples according to Examples 1 to 3 and Comparative Examples 1 and 2, and FIG. 9 is a graph showing the specific surface area of the samples according to Examples 1 to 3 and Comparative Examples 1 and 2 Fig.

[Table 1]

As shown in Table 1 and FIG. 9, the specific surface area of the thermal etching treatment through the N ₂ adsorption / desorption isotherms was measured. As a result, 1, the zeolite nanofibers before the etching process were observed to have a low specific surface area of 210 m ² / g because the zeolite particles were surrounded by the polymer.

On the other hand, in Examples 1 to 3, it was confirmed that the specific surface area was increased so that the thermal corrosion treatment temperature could be increased. Particularly, in Example 3 in which thermal corrosion treatment was performed at 400 ° C, the zeolite powder of Comparative Example 2 And a specific surface area of 816 m ² / g.

From the above experimental results, it can be seen that, in Examples 1 to 3, zeolite nanofibers having flexibility and high surface area were successfully synthesized.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. These changes and modifications may be made without departing from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

S110: Complex solution forming step
S120: electrospinning step
S130: Thermal corrosion step

Claims (12)

(a) adding a porous material to a solvent and stirring, and then adding a polymer resin to form a composite solution;
(b) electrospinning the composite solution on a substrate, followed by drying to form a porous nanofiber composite; And
(c) etching the surface of the porous nanofiber composite by subjecting the porous nanofiber composite to thermal erosion treatment;
Wherein the porous nanofibers have a high specific surface area.
The method according to claim 1,
The step (a)
(a-1) adding the porous material to a solvent and performing ultrasonic treatment for 7 to 8 hours for primary mixing, and
(a-2) secondary mixing the primary mixed products with a stirrer, and
(a-3) adding a polymer resin to the resultant secondary-mixed product, and then subjecting the resultant mixture to tertiary mixing using an agitator, thereby producing a flexible porous nanofiber having a high specific surface area.
3. The method of claim 2,
The secondary mixing was performed at a speed of 200 to 400 rpm,
Wherein the third mixing is carried out at a speed of 1000 to 2000 rpm. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
The method according to claim 1,
In the step (a)
The composite solution
A polymeric resin: 15 to 35% by weight, a porous material: 5 to 35% by weight, and the balance solvent.
The method according to claim 1,
In the step (a)
The porous material
Zeolite, and activated carbon. 2. The method for producing a flexible porous nanofiber according to claim 1, wherein the porous nanofibers have a high specific surface area.
The method according to claim 1,
In the step (b)
The electrospinning
Wherein the composite solution is injected into a syringe and then discharged onto the substrate at a rate of 0.1 to 3.0 ml / hr using a syringe pump. The method for producing a flexible porous nanofiber according to claim 1,
The method according to claim 1,
In the step (b)
The electrospinning
A radiation voltage of 15 to 18 kV, and a spinning distance of 5 to 15 cm. The method of producing flexible porous nanofibers having a high specific surface area.
The method according to claim 1,
In the step (b)
The drying
At 70 to 90 &lt; 0 &gt; C for 5 to 20 hours.
The method according to claim 1,
In the step (c)
The porous nanofiber composite includes a porous material and a polymer resin layer surrounding the porous material, wherein a part of the polymer resin layer is etched by thermal erosion treatment to expose a part of the porous material to the outside A method for producing flexible porous nanofibers having a high specific surface area.
The method according to claim 1,
In the step (c)
The thermal erosion process
At a temperature of 250 to 450 ° C. 5. A method for producing a flexible porous nanofiber having a high specific surface area.
A method for producing a porous nanofiber according to any one of claims 1 to 10,
And a polymer resin layer surrounding a surface of the porous material, wherein a part of the polymer resin layer is etched by thermal erosion treatment, and a part of the porous material is exposed to the outside. Porous nanofiber composite.
12. The method of claim 11,
The porous nanofiber composite comprises
And a specific surface area of 500 to 850 m &lt; 2 &gt; / g.

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